This invention relates to excess flow valves for controlling flow through a conduit wherein the valve minimizes the pressure drop through the valve and also reduces the number of parts typically required.
Excess flow valves are utilized to limit the amount of fluid flow through a conduit. Generally, some way of holding the valve in a generally open position maintains the valve in an open position allowing flow through the conduit if the volume flow through the conduit is below predetermined limit. If the volume flow increases above the limit, or stated another way, if the pressure drop across the valve exceeds a certain value, then the valve is moved to a closed position restricting flow through the conduit.
One type of excess flow valve uses a magnet to hold the valve at a generally opened position. The typical prior art magnetic excess flow valve has been incorporated into a capsule, wherein the entire structure for providing a valve seat, a valve guide, and a magnet holder are all incorporated as a single capsule item.
Inevitably, the prior art has resulted in undesirably high pressure drop across the valve due to the high number of parts received in the flow path in this prior art type valve.
In addition, the prior art valves have had non-symmetric structure such that inadvertent resistance to flow has resulted due to variations in the orientation of the various valve components. This is undesirable.
In disclosed embodiments of this invention, a simplified excess flow valve is provided which results in a relatively small pressure drop across the valve assembly. This is achieved by reducing the number of parts, and eliminating restriction to flow through the conduit due to the valve assembly to the extent possible when the valve is open. In preferred embodiments, a first body portion incorporating a valve guide and a magnet holder is separate from the valve seat. In some embodiments the valve seat may be provided by a separate valve seat, and in other embodiments the valve seat is provided by a surface in one of the conduit halves.
In the second type of inventive embodiments, the valve is preferably mounted at a connection between two conduit portions, such that the valve seat may be provided at one of those two conduit portions. Moreover, there is less structure at the outer periphery of the valve to disrupt or otherwise provide a restriction to flow. Generally, the excess flow valves allow flow around the outer periphery of the valves when the valve is in its open position. The prior art has had structure in the way of the flow, which results in undesirably high pressure drop. The present invention incorporates its valve guiding function with a plurality of circumferentially spaced legs extending radially inwardly from a radially outer portion. This structure presents less of a restriction to flow than the prior art, which generally extends it along the entire circumference of the valve. With the present invention there is thus less disruption or other resistance to flow.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.